The invention is in the field of computers and particularly pertains to the protection of the computer operator from radiation from the video display terminal (hereinafter "VDT").
EMF radiation is currently of great concern to electronics-based societies. The EMF from high-tension wires passing through the countryside has been correlated with an increased incidence of certain cancers of persons working, living or playing beneath the high tension wires, as well as problems with animals which graze beneath the wires, including interference with the reproduction process.
This concern has spread to computers, and particularly to the radiation emitted by the CRT. Clearly, this is not a problem for an occasional computer user, but increasingly many people spend eight hours a day in front of a VDT. Moreover, depending on the type of VDT, there may be a small but significant amount of X-ray and UV leakage as well as EMF. Federal regulations limit X-ray emissions from CRTs to no more than 0.5 mR/hr. It is somewhat early to make firm conclusions about the long-term effects of prolonged exposure to the radiation from VDTs, and for this very reason there is a movement afoot to provide protection from the cumulative effects of this potentially harmful radiation. Of special concern is the unknown but potential harm done to pregnant women. In addition to the long-term effects, there is mounting evidence that high-frequency radiation causes eye strain.
Although some screens have been provided with VDT shields which attach to the front of the VDT, it is believed that these are not very effective in stopping EMF, glare and other harmful high-frequency radiation such as X-rays. Whereas the low-level X-rays produced by the VDT are currently of less concern than the EMF, the synergistic effects of the combination is an unknown.
In addition to the VDT shields, VDT eyeglasses have been produced which eliminate UV and reduce glare. However, they do not provide body protection at all, and they reduce the visible light to the eye.
Thus, for the most part, despite the current concern about prolonged computer use, the typical computer operator nonetheless remains essentially unprotected from the VDT radiation. In addition to the radiation danger, continual use of computers is very hard on the eyes, largely because of incident glare from ambient light sources, both directly on the eye and reflected from the VDT screen. The eye strain and possible eye damage is particular acute for those who do not have perfect vision, with the most distress being experienced as a progressive function of increased refractive correction requirements for any particular operator.
The glare from ambient light causes the pupil to contract so that it is under a constant strain inasmuch as pupillary muscles are used to make this contraction. Once the pupil is contracted, which is caused automatically by the net amount of light admitted to the eye which includes glare, then the image that the computer operator wishes to see may not be bright enough, since as it is the glare that is causing pupillary contraction more than the computer image.
Some computer operators report considerable eye strain, with redness and swelling in the eye areas and perhaps tearing, after only an hour or two of use of a computer if the glare is particularly bad. Others go for longer periods of time, but the problem is universal in nature.